1. Field of the Invention
The present invention relates to a technique for establishing transmission paths meeting a guaranteed bandwidth requirement in an information network, with backup or restoration in the event of an active path link failure.
2. Discussion of the Known Art
Emerging trends in backbone and transport networks require network providers to guarantee that backup paths meeting a certain guaranteed bandwidth will be deployed quickly in the event of active path failures.
For example, and without limitation, consider a Multi-Protocol Label Switched (MPLS) application. In MPLS, a data packet is “encapsulated” at an ingress node (e.g., a first network router), and is given an IP header label. The header label is used to forward the packet along a label-switched path (LSP) or “tunnel” to a destination node (e.g., a second network router). The tunnels may be regarded as virtual point-to-point links between two edge nodes (e.g., the first and the second routers) which may actually be separated by a number of links between successive nodes within a given network. See, e.g., L. L. Peterson, et al., Computer Networks, Morgan Kaufmann Publishers (2d ed. 2000), at 277-80.
Restoration mechanisms create backup paths for redirecting traffic in the event of an active path failure. The backup paths typically are set up simultaneously with the active paths. It therefore becomes necessary to define both an active path and a backup path to satisfy each request for a restorable, bandwidth-guaranteed LSP. The known restoration mechanisms operate in a static manner, i.e., sets of active and backup paths are defined under the assumption that future demands are known. This assumption has a drawback in that network resources are used potential future demands that can be routed. Accordingly, there is a need for a restoration mechanism that operates dynamically, wherein an active and an associated backup path are determined for each request as it arrives, and in such a manner as to use available network resources efficiently.